1. Field of the Invention
The present invention relates to a rotating connector which is incorporated in a steering system of an automobile and which is used as electrical connecting means for an air bag system or the like.
2. Description of the Related Art
Rotating connectors are formed by connecting a pair of housings, which are concentrically and relatively rotatably coupled to each other, through a belt-like flexible cable. They are roughly categorized into two types depending on the way in which the flexible cable is wound. In the first type, the flexible cable is wound like a whirl in an annular accommodating portion defined by the pair of housings. In the second type, the flexible cable is wound in a reverse direction in the accommodating portion. In the second type, the required length of the flexible cable can be made shorter. Therefore, the second type has the advantage of reduced total costs.
However, in conventional rotating connectors, when the flexible cable is subjected to vibrations from the automobile and moves vertically in the accommodating portion, both widthwise direction ends of the flexible cable collide with the upper case and the lower cover of the first housing, resulting in the generation of noise unpleasant to the ear.
To try to solve this problem, the applicant proposed a rotating connector in European Patent Publication No. EP0770521A1. The rotating connector comprises a first housing and a second housing concentrically and relatively rotatably coupled together; a belt-like flexible cable which is wound in a reverse direction through an annular accommodating portion defined by the housings, with both ends of the flexible cable being secured to the housings; and a movable body which is rotatably disposed in the accommodating portion and which has a hole through which the turning portion of the flexible cable passes. In the rotating connector, an outer extension portion is formed at the movable body so as to oppose the widthwise direction ends of the flexible cable. The flexible cable is held down at the outer extension portion to reduce the noise level.
FIG. 9 is a partial plan view showing in section a portion of the first housing side connecting portion of the flexible cable of the proposed rotating connector. FIG. 10 is a sectional view taken on line 10--10 of FIG. 9.
As shown in FIG. 9, a flexible cable 4 crosses at point P an outer extension portion 17b of a lower holder 17 (see FIG. 10) of a movable body, and extends up to a stationary side connecting portion 31 provided at an upper case 8 (see FIG. 10) of a first housing. A connecting end portion of the flexible cable 4 is secured to the stationary side connecting portion 31. Reference numeral 18 denotes a roller of the movable body.
However, in this structure, the outer extension portion 17b of the lower holder 17 contacts an edge of the flexible cable 4 at point P (of FIG. 9), as shown in FIG. 10. Therefore, when sliding occurs at the portion where they contact each other, noise is generated.